A reamer of this type is disclosed in U.S. Pat. No. 4,040,765. In this design the reamer has an interchangeable cutter head with a conical butt which is inserted in a matching conical socket in the reamer shank. The cutter head is screwed to the reamer shank via a screw bolt. The conical engagement between the cutter head and the reamer shank ensures a connection free from play. However, this arrangement has the drawback that, particularly in the case of fairly strong feeding forces, the cutter head is pressed into the reamer shank and jams, especially because the conical engagement is also self-locking. The cutter head is hard to remove from the reamer shank, whereby the union pin in particular is subjected to great wear and tear. In this reamer there is no provision for equipping the cutter heads with coolant means. It is also not evident how coolant means could be incorporated in this reamer, especially not coolant means having exits adjacent the cutting edges. Furthermore, since the conical butt has an internal thread, the cutting head and conical butt cannot be made as a one piece integral member by form pressing and sintering a carbide powder.
Another example of such a reamer disclosed in U.S. Pat. No. 5,163,790. The reamer has an interchangeable cutter head and a coolant-lubricant feed supplying the cutter head from an annular nozzle disposed far from the cutting blades. The cutter-head shank is cylindrical and is retained in an opening of the reamer shank and is secured thereto by means of a clamping bolt passing through the cutter head. The clamping bolt includes a recessed hexagon by means of which the clamping bolt can be screwed in and out. To replace the cutter head the clamping bolt has to be disadvantageously completely removed from the reamer shank. In this reamer there is no provision leading coolant to the cutter head. Moreover, when replacing a cutter head and tightening the clamping bolt to secure the cutter-head in position, there is no guarantee that the clamping bolt will end up in the same rotationally oriented position each time. Therefore, even if the coolant were to be somehow supplied to the head of the bolt and radially directed coolant apertures were provided in the head of the bolt, it would not be certain that the apertures would aligned with the cutter-head cutting edges every time a cutter head was secured in position. Furthermore, if instead of cutter blades secured to the cutter head, it was desired to form a one piece integral cutter head and shank from solid carbide, the elongated form of the cutter head together with the cutter-head shank makes it very difficult to form press and sinter.